1. Field of the Invention
The present invention relates to an antenna device of a mobile terminal having a case, and more particularly, to an antenna device of a mobile terminal providing an antenna pattern in a case.
2. Discussion of the Background
Generally, a mobile terminal is an electronic device enabling a user to perform a function, such as wireless communication, network connection, and digital broadcasting reception without limitation to time. The mobile terminal includes an antenna device required for communication. The antenna device may be a conductive wire protruding out of the mobile terminal to emit an electric wave in space or to induce an electromotive force by an electric wave for wireless communication.
Hereinafter, a conventional antenna device of a mobile terminal for viewing terrestrial digital broadcasting is described with reference to the accompanying drawings.
FIG. 1 is a perspective view illustrating a mobile terminal having a conventional antenna device for terrestrial digital broadcasting. FIG. 2 is a perspective view illustrating a conventional external antenna device for digital broadcasting of a mobile terminal.
Terrestrial digital broadcasting uses a signal whose central frequency is 200 MHz in a frequency band of 184 MHz to 216 MHz. Accordingly, a wavelength, λ, is 1.5 m, and a proper antenna length is λ/4, i.e., 37 cm. An antenna whose antenna length is λ/4, i.e., 18 cm, may also be used.
Terrestrial digital broadcasting antenna 110 has a long length. In use, terrestrial digital broadcasting antenna 110 protrudes outside of mobile terminal 100, as shown in FIG. 1.
Accordingly, mobile terminal 100 may include a space to hold terrestrial digital broadcasting antenna 110 therein. Because it may be difficult to decrease a size of mobile terminal 100 and because terrestrial broadcasting antenna 110 protrudes outside of mobile terminal 100, antenna 110 may break when moving mobile terminal 100 while employing digital broadcasting; thus, it may be inconvenient to use mobile terminal 100.
In order to solve the aforementioned problem and to improve the appearance of mobile terminal 100, an antenna which does not protrude outside of mobile terminal 100, but may be provided inside mobile terminal 100, may be used. However, because an antenna, such as a terrestrial digital broadcasting antenna 110, operating in a low frequency band has a long length, it may be very difficult to enclose terrestrial digital broadcasting antenna 110 inside mobile terminal 100.
In order to solve the aforementioned problem, as shown in FIG. 2, external antenna device 210 for digital broadcasting coupled to mobile terminal 100 may be used. External digital broadcasting antenna device 210 may be coupled to mobile terminal 100 using coupling projection 211, which may be inconvenient for the user.